Certain types of industries, commonly referred to as "light industrial" and certain commercial areas such as supermarkets etc. can advantageously employ luminaires with a relatively large amount of upward light, that is light emitted above horizontal or just below horizontal. Such areas generally have either finished ceilings or a truss area painted a light color. Thus a large percentage of the uplight is reflected down to the work surface.
Providing a higher percentage of uplight in these types of areas produces several advantages such as:
(a) superior appearance of the environment due to greater illumination on ceiling and vertical surfaces; PA1 (b) reflected light from ceilings and walls results in more light from more directions reaching a work area; and PA1 (c) better vertical surface lighting.
Prior to the present invention luminaires using HID light sources to produce large percentages of uplight do so by utilizing leakage light through prismatic glass reflectors. Thus, the uplight has been generally uncontrolled and the illumination on the ceiling is not uniform and usually has a very hot spot directly above the luminaire.
The present invention utilizes a refracting medium of glass or plastic with prismatic structures such that the upward light is controlled to produce a uniformly lit ceiling area.